12.0 DOCSIS Cable Modem (CX150/180 models only)
Background:
Historically, CATV was a unidirectional medium designed to carry broadcast analog video channels to the
maximum number of customers at the lowest possible cost. With the introduction of direct broadcast satellite (DBS) and digital
subscriber line (DSL) during the 1990s, cable operators experienced a serious challenge from these competing technologies - DBS
operators marketed more choice and better quality entertainment product through digital technology, whereas the incumbent local
exchange carriers (ILEC) proposed to offer a combination of voice, video, and data by means of DSL.
This economic and technical threat prompted several key multiple system operators (MSOs) to define a new system and standard
capable of providing data and future services over CATV plants. The Data Over Cable Service Interface Specification (DOCSIS) 1.0
standard that resulted was unanimously accepted as the North American standard, and vendors aggressively introduced products in
compliance with this standard. MSOs in turn defined upgrade and construction programs to increase the supporting bandwidth of
their plants and to provide two-way functionality. The DOCSIS standards have evolved continuously and are proving to be a
universal success, with many deployments in operation worldwide.
The DOCSIS interface specification basically enables the deployment of data-over-cable systems on a nonproprietary, multivendor,
interoperable basis for transparent bidirectional transfer of Internet Protocol (IP) traffic between the cable system head end and
customer locations over an all-coaxial or hybrid-fiber/coax (HFC) cable network. In its simplest form, the system consists of a
Cable Modem Termination System (CMTS) located at the head end, a coaxial or HFC medium, and a Cable Modem (CM) located
at the customer premises. In addition, DOCSIS defines physical, signaling and protocol layers to support interoperability and
evolutionary feature capabilities to permit future value-added services.
CX100/110/120/150/180 series e-Manual D07-00-002 Rev B01
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